Snorkel-equipped loading boom with safeguard against destructive bending of snorkel



Sept. 16, 1969 J. R. THOMPSON 3,467,250

SNORKEL-EQUIPPED LOADING BOOM WITH SAFEGUARD AGAINST DESTRUCTIVE BENDINGOF SNORKEL Filed July :51, 1967 2 Sheets-Sheet 1 FIG IN VENTOR. JAMESRUSSELL THOMPSON ATTORNEYS Sept. 16, 1969 J. R. THOMPSONSNORKEL-EQUIPPED LOADING BOOM WITH SAFEGUARD AGAINST DESTRUGTIVE BENDING0F SNORKEL 2 Sheets-Sheet 2 Filed July 31, 1967 JAMES RUSSELL THOMPSONINVENTOR.

ATTORNEYS United States Patent 3,467,260 SNORKEL-EQUIPPED LOADING BOOMWITH SAFEGUARD AGAINST DE- STRUCTIVE BENDING OF SNORKEL James R.Thompson, Seattle, Wash., assignor to Washington Iron Works, Seattle,Wash., a corporation of Washington Filed July 31, 1967, Ser. No. 657,369Int. Cl. B66c 1/32, 23/06, 23/66 US. Cl. 2127 7 Claims ABSTRACT OF THEDISCLOSURE The invention relates to an overload protector for thesnorkel of a snorkel-equipped log-loading boom, and aims to provide amechanism of a simple and inexpensive construction which willeffectively protect the snorkel, which has the log grapple suspendedfrom its outer end, against liability of being subjected todestructively heavy loads such as that of a log while the snorkel is inan extended position.

With this and other objects and advantages in view and which will appearand be understood in the course of the following description and claims,the invention consists in the novel construction and in the adaptationand combination of parts hereinafter described and claimed.

In the accompanying drawings:

FIGURE 1 is a side elevational view illustrating structure embodying thepreferred teachings of the present invention in its working environmentwith a snorkelequipped loading boom, the boom being shown in phantOIIl.

FIG. 2 is a fragmentary enlarged-scale top plan view showing the outerend of the snorkel.

FIG. 3 is a fragmentary side elevational view of the snorkel.

FIGS. 4 and 5 are transverse vertical sectional views drawn to anenlarged scale on lines 44 and 55, respectively, of FIG. 3; and

FIG. 6 is an enlarged-scale view similar to FIG. 2 with parts brokenaway and shown in section with the cable deleted.

Referring to said drawings, the numeral 10 denotes a foundation on whichthere is mounted a turntable 11. The turntable gives pivot support tothe inner end of a vertically swingable loading boom 12 and carries aplurality of spooling drums together with an engine for powering theturntable, the spooling drums, an air compressor, and a hydraulic pump.Compressed air controls the drums and a reversible valve for a hydraulicmotor which operates a snorkel appendage for the boom. There are threedrums related to the loading operation. The boom is raised and loweredby operation of a drum 13. Drum 14 handles a load line 15 for atong-grapple 16, and drum 17 handles a holding line 18 for said grapple.The load line runs directly to the grapple from sheaves 20 located atthe outer end of the boom. The holding line 18 passes over a sheave 21which is hung by a line 22 from the outer end of the snorkel.

Functionally considered, the snorkel of the present invention is like orsimilar to that illustrated and described in US. Patent No. 2,878,946,and this is to say that an outer leg 23 of the boom has a telescopingassembly supported thereon. This assembly comprises a reach section 24received for endwise motion within a mount section 25 with the reachmovement being in an outward direction relative to the boom along anaxis generally paralleling said outer leg of the boom.

Rollers 26 and 27, the former carried by the reach member at its innerend and tracking against the top wall of the mount section and thelatter carried by the mount section and tracking upon the underside ofthe reach section, guide the reach section in its endwise motion. Thereach section 24 is powered in its extension and retraction movements bya double-acting hydraulic jack. The cylinder 28 of the jack has its rearend pivoted at 29 to the mount section 25. The piston rod 30 of the jackis pivoted at 31 to lugs 32 made integral with the reach section.Rollers 33 support the cylinder 28 at its outer end, riding upon thebottom wall of the reach section.

A yoke-shaped bracket 34 is bolted or otherwise rigidly secured to thereach section at its extreme outer end. A shaft 35 extends transverselybetween the yoke arms with its ends journaled between the base and capcomponents of split blocks. Journaled on the shaft is a winding drum 37,and keyed to the shaft and acting in complement to normally hold thedrum against rotation are a pressure plate and a thrust plate 41. Thepressure plate carries a friction surfacing 42 which bears against anend face of the drum, and the thrust plate acts through Bellevillesprings 43 to adjustably tension the pressure plate, the adjustmentbeing afforded by a nut 44 working on a threaded portion of the shaft.When the nut is turned in a right-hand, or tension-increasing, directionthe shaft and the two plates keyed thereto are held against rotation bya dog 45 which catches behind one of a set of ratchet teeth 46 formed inthe perimeter of the pressure plate. A removable pin 47 locks the dog inthis position. The aforementioned sheave 21 is made a part of a fittingwhich includes a track sheave 48, and the latter is caught in a loop ofthe line 22. One end of the looped line is anchored at 50 to the outerend of the snorkel. The other end is wound on the drum 37, with thedirection of wind such that a ratcheting action of the friction-coupleddrum and plate assembly 37-40-41 takes in on the line.

The setting given to the thrust plate by a turning of the adjusting nut44 is that which will give to the friction couple a resistance loadingsufiicient to counter no more than a downward pull of given intensity towhich the sheave 21 may be subjected, from the holding line 22, when thesnorkel occupies its extended position. This given pull represents apredetermined limit of terminal loading which the extended snorkel cansafely carry without liability of becoming damaged.

It will be understood that the operator, having extended the snorkel tobring the tong grapple into proximity of a log which is to be heeledagainst the boom incident to loading the log upon the bed of a truck,retracts the snorkel before pulling the log toward the boom. Asnorkel-damaging overload can of course occur through negligence of theoperator should he fail to retract the snorkel before taking in on theload and hold-- ing lines. More frequently, however, the cause lies inthe fact that when the grapple is applied to a log the weight of thegrapple causes the log to roll so that there is passed into the holdingline 22 a heavy loading force, which is nnassociated with any operationof the spooling drums, before the operator has been enabled to retractthe snorkel. The automatic slippage afforded by the adjustable frictioncouple of the present invention protects against damage to the snorkelregardless of the overloading cause.

It is believed that the invention will have been clearly understood fromthe foregoing detailed description of my now-preferred illustratedembodiment. Changes in the details of construction may be'resorted towithout departing from the spirit of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In combination with a loading machine of the character describedhaving a hinged loading boom with cableways at the outer end andextensible in point of its range by an extensible snorkel which iscarried upon the boom in non-hinging relationship and has a cable-way atthe outer end, providing power-driven means on which a loading cable anda holding cable are spooled, and having a log-engaging means to whichthe outer ends of 'both cables are secured, the loading cable runningfrom the spooling means through a cable-way of the boom and thendirectly to the log-engaging means, the holding cable running from thespooling means through a cable-way of the boom and then through thecable-way of the snorkel before connecting with the log-engaging means,said snorkel when extended being structurally incapable of supportingloads in the holding cable typically borne by the boom through theloading cable: a mechanism acting automatically to relieve tension inthe holding cable sufficient to preclude destructive bending of thesnorkel in the circumstance of an engaged log passing through said cableinto the outer end of the snorkel while the snorkel is in an extendedcondition a load in excess of a predetermined safe limit.

2. The combination of claim 1 in which the cable-way of the snorkel isprovided in a block suspended from the outer end of the snorkel by acable having its other end spooled upon a winding drum, thetension-relieving mechanism comprising a friction plate located co-axialto the drum and exerting upon an end face of the drum an endwisepressure of predetermined intensity, means being provided holding thefriction plate against turning motion in the unwinding direction of thedrum.

3. The combination of claim 2 in which the endwise pressure exerted bythe friction plate admits of being pre-set to selected intensities.

4. The combination of claim 2 in which said holding means comprises adog functional to the teeth of a ratchet wheel which is secured to thefriction plate.

5. The combination of claim 2 in which said holding means comprises adog functional to the teeth of a ratchet wheel which is secured to thefriction plate, a releasable means being provided for locking the dog ina toothcatching position.

6. The combination of claim 2 in which the drum and tension-relievingmechanism are mounted upon the outer end of the snorkel.

7. The combination of claim 1 in which the automatically actingmechanism comprises means responsive to tension in the holding cableabove a predetermined limit applied to the drum.

References Cited UNITED STATES PATENTS 2,704,191 3/1955 Schley.2,917,278 12/1959 Arnold 254150 3,011,651 12/1961 McIntyre 2l2-73,051,447 8/1962 Ahlbin 254-187 3,301,533 1/1967 Pfaff 254187 EVON C.BLUNK, Primary Examiner H. C. HORNSBY, Assistant Examiner US. Cl. X.R.

